SSE sounds bad in UL - diyAudio
Go Back   Home > Forums > Commercial Sector > Vendor Forums > Tubelab

Tubelab Discussion and support of Tubelab products, prototypes and experiments

Reply
 
Thread Tools Search this Thread
Old 25th April 2015, 01:54 PM   #1
diyAudio Member
 
Join Date: Dec 2014
Default SSE sounds bad in UL

Sounds great in triode mode with cathode feedback, but ultralinear sounds terrible. Any ideas from those who have been down this road before? I'm using the big edcors and mullard KT88's.
  Reply With Quote
Old 25th April 2015, 03:24 PM   #2
diyAudio Member
 
Join Date: Oct 2006
Please could you describe what you're hearing that is leading you to your conclusions?

I am not disagreeing with you, but am interested - my SSE has only been wired in triode mode as yet with EH KT88's and zero feedback.

Thanks,
Charlie
  Reply With Quote
Old 25th April 2015, 03:50 PM   #3
diyAudio Member
 
Join Date: Dec 2014
The amp is certainly louder in UL, but distortion is unbearable even as less than half volume. It's so bad that it would make a good guitar amp!
  Reply With Quote
Old 27th April 2015, 11:33 PM   #4
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Have you checked with an oscilloscope to see whether the amplifier is oscillating? (You'll come back and tell me that you don't have an oscilloscope - can you find someone who does?) Are you sure your cathode feedback is correctly phased?
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 27th April 2015, 11:47 PM   #5
diyAudio Member
 
Join Date: Dec 2014
You are correct that I don't have a scope. I can borrow one from work. Not sure on the feedback phasing. Can you talk me through the scope checks?
  Reply With Quote
Old 28th April 2015, 08:45 PM   #6
w5jag is offline w5jag  United States
diyAudio Member
 
Join Date: Feb 2007
Location: Arkansas
Quote:
Originally Posted by kevinkr View Post
Are you sure your cathode feedback is correctly phased?
That was the first thing I thought of.

I know when I had the Transcendars on my first SSE, and I was playing around with it in pentode, I could make it oscillate with the cathode feedback backwards. The oscillation was obvious, though - it squealed like a pig.

After awhile, I swapped out for 125 ESE's to take advantage of the different loads, and they hook up easy - just pick an unused secondary and connect it to the cathode feedback point on the board.

I have my low power SSE running 2E26's in UL and have not heard any unusual distortion in it with the small Edcors, but, I do not have the cathode feedback enabled. UL is enough feedback for me.

The cathode feedback seemed subtle to me - the 125 ESE's do benefit from it, but I would think with a better class of OPT's, it wouldn't add much.

Win W5JAG

Last edited by w5jag; 28th April 2015 at 08:49 PM.
  Reply With Quote
Old 28th April 2015, 08:55 PM   #7
w5jag is offline w5jag  United States
diyAudio Member
 
Join Date: Feb 2007
Location: Arkansas
Quote:
Originally Posted by chilihed View Post
The amp is certainly louder in UL, but distortion is unbearable even as less than half volume. It's so bad that it would make a good guitar amp!
It will be more sensitive in UL than it would be in triode. What are you driving it with? Are you overdriving it?

Win W5JAG
  Reply With Quote
Old 28th April 2015, 09:04 PM   #8
diyAudio Member
 
Join Date: Dec 2014
Driving it with a direct source DVD player.
  Reply With Quote
Old 28th April 2015, 09:40 PM   #9
w5jag is offline w5jag  United States
diyAudio Member
 
Join Date: Feb 2007
Location: Arkansas
Have you tried it without the CFB enabled?

Win W5JAG
  Reply With Quote
Old 28th April 2015, 09:49 PM   #10
diyAudio Member
 
Join Date: Dec 2014
No it's always been with CFB.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
10w Transcendar SSE (non-UL) lordearl Tubelab 2 28th March 2015 02:07 AM
SSE pentode/triode/UL neomat Tubelab 7 22nd July 2012 02:58 PM
SSE/KT-88/Transcendar OPT: UL? CFB? Why? dagerman Tubelab 2 10th September 2011 04:17 PM
SSE triode/UL wiring help please Horsebox Tubelab 2 10th May 2011 06:36 PM
Check my SSE's Triode/UL and CFB Switch Connection Junior Tubelab 19 17th April 2010 02:58 AM


New To Site? Need Help?

All times are GMT. The time now is 06:17 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.
Copyright 1999-2015 diyAudio

Content Relevant URLs by vBSEO 3.3.2